Generally speaking, for as much hype and passion exists within the fighting game community, it's one of the more problematic spaces in the gaming world as well. Not only has the community itself long suffered from being a safe space for some of the worst jerks you can imagine, but developers themselves seem to have a real hit-or-miss relationship with their own fans and players. Nintendo is probably the biggest example, as they routinely ignore and even suppress the vibrant fighting scene that's grown around their iconic Super Smash Brothers franchise, but other studios can cause problems as well.
In this case, it was NetherRealms, who appear to have decided to actually ban a player from a tournament because he made fun of them mid-match.
The player in question was finalist Titaniumtigerzz, who was playing Shiva, one of the more powerful competitors in the current roster. The problem wasn't with anything he said, but rather, with the customized name he had given to the customized move set he had made for Shiva, which was "WhyDidNRSdoThis.". A reference, no doubt, to the fact that many people consider Shiva to be broken at the moment thanks to her powerful, unblockable jump attack.
In any case, a few minutes into the stream, things cut to black, and it was announced Titaniumtigerzz was disqualified due to being "disrespectful". And since that was the only thing that could have possibly been construed as disrespectful in the stream, well... people have drawn conclusions.
Neither NetherRealm of WB Games have commented on the ban, and while the rules of the tournament never specifically said players have to be nice to NetherRealm, it also says the developers can pretty much ban whoever they want for whatever reason, so, it's not like they're going to get much blowback in that sense.
That said, now that "WhyDidNRDoThis" is trending on Twitter, clearly they forgot how the internet works.